VERTICAL AND NEAR-VERTICAL INCIDENCE OF P-WAVES IN A LAYERED SOLID

This article gives two analytical expressions of the displacement in a flat structure: one based on Cagniard's method for simpler cases, the other using a Fourier integral for more general cases. The numerical experiments aimed to check the methods by comparing zero-offset cases with cases of near-vertical incidence confirm the existence of longitu dinal PS waves as obtained by Hron and his collaborators. In addition, the experiments reveal that the longitudinal motion of the PS waves i s the limit of an elliptical-like particle motion associated with the PS waves for near-vertical incidence. It turns out that this unusual p article motion tends to the classical transverse rectilinear motion wh en the source-receiver offset is large enough. A similar behavior was found for the particle motion associated with the reflected PS, P2S, a nd PS2 for small offset receivers located on the free surface of a sol id consisting of one homogeneous layer over a half-space.